png.c

#include "config.h"

#ifdef FBV_SUPPORT_PNG
#include "fbv.h"
#include <stdlib.h>
#include <string.h>
#include <png.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

#define PNG_BYTES_TO_CHECK 4
#ifndef min
#define min(x,y) ((x) < (y) ? (x) : (y))
#endif

int fh_png_id(char *name)
{
	int fd;
	char id[4];
	fd = open(name, O_RDONLY);
	if(fd==-1) return(0);
	read(fd, id, 4);
	close(fd);
	if(id[1]=='P' && id[2]=='N' && id[3]=='G') return(1);
	return(0);
}


int fh_png_load(char *name, unsigned char *buffer, unsigned char ** alpha,int x,int y)
{
	png_structp png_ptr;
	png_infop info_ptr;
	png_uint_32 width, height;
	png_uint_32 i;
	int bit_depth, color_type, interlace_type;
	int number_passes,pass, trans = 0;
	png_bytep rptr[2];
	unsigned char *rp;
	unsigned char *fbptr;
	FILE *fh;

	if(!(fh = fopen(name,"rb"))) return(FH_ERROR_FILE);

	png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,NULL,NULL,NULL);
	if (png_ptr == NULL) return(FH_ERROR_FORMAT);
	info_ptr = png_create_info_struct(png_ptr);
	if (info_ptr == NULL)
	{
		png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
		fclose(fh);
		return(FH_ERROR_FORMAT);
	}
	rp = 0;
	if (setjmp(png_jmpbuf(png_ptr)))
	{
		png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
		if(rp) free(rp);
		fclose(fh);
		return(FH_ERROR_FORMAT);
	}

	png_init_io(png_ptr,fh);

	png_read_info(png_ptr, info_ptr);
	png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, &interlace_type, NULL, NULL);
	if (color_type == PNG_COLOR_TYPE_PALETTE) png_set_expand(png_ptr);
	if (bit_depth < 8) png_set_packing(png_ptr);
	if (color_type == PNG_COLOR_TYPE_GRAY || color_type== PNG_COLOR_TYPE_GRAY_ALPHA) png_set_gray_to_rgb(png_ptr);
	if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
	{
		trans = 1;
		png_set_tRNS_to_alpha(png_ptr);
	}

	if(bit_depth == 16) png_set_strip_16(png_ptr);
	number_passes = png_set_interlace_handling(png_ptr);
	png_read_update_info(png_ptr, info_ptr);

	if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA || color_type == PNG_COLOR_TYPE_RGB_ALPHA || trans)
	{
		unsigned char * alpha_buffer = (unsigned char*) malloc(width * height);
		unsigned char * aptr;

		rp = (unsigned char*)malloc(width * 4);
		rptr[0] = (png_bytep) rp;

		*alpha = alpha_buffer;

		for (pass = 0; pass < number_passes; pass++)
		{
			fbptr = buffer;
			aptr = alpha_buffer;
			for(i=0; i<height; i++)
			{
				png_uint_32 n;
				unsigned char *trp = rp;
		   		png_read_rows(png_ptr, rptr, NULL, 1);
				for(n = 0; n < width; n++, fbptr += 3, trp += 4)
				{
					memcpy(fbptr, trp, 3);
					*(aptr++) = trp[3];
				}
			}
		}
		free(rp);
	}
	else
	{
		for (pass = 0; pass < number_passes; pass++)
		{
			fbptr = buffer;
			for(i=0; i<height; i++, fbptr += width*3)
			{
				rptr[0] = (png_bytep) fbptr;
		   		png_read_rows(png_ptr, rptr, NULL, 1);
			}
		}
	}
	png_read_end(png_ptr, info_ptr);
	png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
	fclose(fh);
	return(FH_ERROR_OK);
}


int fh_png_getsize(char *name, int *x, int *y)
{
	png_structp png_ptr;
	png_infop info_ptr;
	png_uint_32 width, height;
	int bit_depth, color_type, interlace_type;
	char *rp;
	FILE *fh;

	if(!(fh=fopen(name,"rb"))) return(FH_ERROR_FILE);

	png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (png_ptr == NULL) return(FH_ERROR_FORMAT);
	info_ptr = png_create_info_struct(png_ptr);
	if (info_ptr == NULL)
	{
		png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
		fclose(fh);
		return(FH_ERROR_FORMAT);
	}
	rp = 0;
	if (setjmp(png_jmpbuf(png_ptr)))
	{
		png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
		if(rp) free(rp);
		fclose(fh);
		return(FH_ERROR_FORMAT);
	}

	png_init_io(png_ptr,fh);
	png_read_info(png_ptr, info_ptr);
	png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, &interlace_type, NULL, NULL);
	png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
	*x = width;
	*y = height;
	fclose(fh);
	return(FH_ERROR_OK);
}
#endif /*FBV_SUPPORT_PNG*/